Hi all;
I am not any type of expert but I just had my first dealings with SATA Drives And Vista also;
I did a lot of googling & got a dual boot finally. what i ended up doing was take my SATA Drive & made into 2- partitions,left both "unallocated";Ran my HP Vista restore disks & put vista on the first partition,when I was finished it had taken the first partition & made a 10gb Restore Partition  & the balance was the SYSTEM partition.=C:\ & D:\.
It would only let me convert the rest of the drive into a SIMPLE Volume,I needed a Primary Partition to install XP, Vista doesn't Like another Primary after it.I googled it & there are posts on how to use Vista's System to turn Unallocated space into a Primary Partition;I think it was "DelPart" Its part of VISTA,I then installed XP & set it all up;On my computer You hit "esc" to choose boot options,I booted into C:\Vista.
 I had already found a SMALL program on my googling "EasyBCD" which has simple Instructions on running it & it rewrites Vistas Bootloader so you have a choice just like XP to 2K,ECT.
I now have C:\Vista, D:\Restore E:\XP.It works Beautiful. Just GOOGLE" install XP after Vista allready Installed..Some sites say you can't, but once you get all the info it was quiet simple.
The only programs I needed was the Vista restore Disks,The XP Install disks & The "EasyBCD" Program.
Maybe help someone out.   
                                   Lencojoe   

P.S. see  APCMAG.COM =How to.  
Lencojoe, thanks for the info, but I all ready have the new HD so I am going to do it on that.I am going to go and try this tomorrow. Let me just make sure: The LINK I sent you guys with the HP thing. The drivers for Vista are the ones I should download, even for HP? or should I go directly to the CHIPSET website and see if anything is there?